A 72-year-old woman with 3 days of bright red rectal bleeding, preserved cardiac function, fever of 103°F, left-lower-quadrant tenderness, and hypotension. What is the most likely diagnosis?

• A. Diverticulitis
• B. Ischemic colitis
• C. Bowel obstruction
• D. Anal fissure

Answer: (A)

Left-sided diverticular inflammation fits best. In an older patient, pain in the left lower quadrant along with fever and a systemic inflammatory response points to diverticulitis, which is inflammation (and sometimes infection) of diverticula in the sigmoid colon. The hypotension here suggests possible sepsis from a complicated infection rather than cardiogenic shock, given preserved cardiac function. Rectal bleeding can occur with diverticulosis/diverticulitis, though the fever and localized LLQ tenderness are more diagnostic cues.

Ischemic colitis tends to present with abrupt abdominal pain and often occurs in patients with vascular disease; fever is less prominent, and the pain is not as specifically localized to the left lower quadrant. Bowel obstruction would cause cramping pain with abdominal distension, vomiting, and altered bowel sounds rather than focal LLQ tenderness with high fever and systemic sepsis signs. Anal fissure causes painful bowel movements with bright red bleeding but lacks fever, LLQ tenderness, and systemic illness.